Bimetallic strip



Aug. 29, 1939. L. M. PERSONS 2,171,344

BIMETALLIQ STRIP Filed Jan. 15, 19:57

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arm e 47-7-0 IVA/6K Patented Aug. 29, 1939 UNITED STATES BIDIETALLIO STRIP Lawrence M. Persons, St. Louis, Mo., assignor, by

mesne assignments, to Automatic Control Gorporation, St. Louis, Mo., a corporation of Delaware Application January 13, 1937, Serial No. 120,379

1 Claim.

The present invention relates generally to a bimetallic strip and a method of making the same, and more particularly to a bimetallic lever or blade and a method of constructing the blade.

An object of the present invention is to provide a blade which comprises two metal strips having different coefficients of expansion, one of said strips being of a greater length than the other.

Another object is the provision of a method of making a bimetallic lever or blade.

Another object is to provide a bimetallic blade having means for preventing a free end from curling upon the application of heat to the blade.

Another object is to provide a bimetallic blade of light metal strips. having means for effecting longitudinal reinforcement.

Another object is to provide a bimetallic blade which is inexpensive, simple to manufacture and Which achieves all of the advantages and objects sought therefor.

Other objects and advantages will be apparent from a consideration of the following description, taken in conjunction with the accompanying drawing, in which Fig. 1 is a plan view of a preferred embodiment of a bimetallic blade constructed in line with the present invention.

Fig. 2 is a side elevation of the bimetallic blade shown in Fig. 1.

Fig. 3 is a section on the line 3-3 of Fig. 1.

Fig, 4 is a section on the line 4-4 of Fig. 1.

Fig. 5 is a side elevation of the bimetallic blade of Fig. 1 showing one end thereof returned to provide a support for a screw, or the like, and the other end returned to provide a spaced supporting section for the blade.

Fig. 6 is a side view of the blade shown in Fig. 5 in cooperative association with a pivoted lever having a contact at one end thereof.

Referring more particularly to the drawing by reference numerals, I indicates generally a bimetallic blade constructed in line with the pres ent invention. The blade I0 comprises a metal strip H having a relatively high coeflicient of expansion and a metal strip l2 having a relatively low coeflicient of expansion. The strip I2 is shorter longitudinally than the strip ll, terminating at the point l3. The instant blade [0 is of a plan configuration shown in Fig. 1, being rectangular throughout the major portion of its length. The metal strip H includes an integral projection I4 at one end which is set off from the main body by the converging boundary lines and l6.

Adjacent that end of the blade having the projection I4, there is a rib I! which is of suflicient length to extend a predetermined degree beyond the point l3 into the bimetallic construction, as can be readily appreciated from an inspection of Fig. 4. The rib I1 is pressed from one surface of the blade I0 and serves both to strengthen the free end of the strip II and to prevent curling of the bimetallic body of the blade l0 adjacent the point l3. The use of light metals is unsatisfactory where such a rib is omitted, inasmuch as positive action of the blade cannot be obtained, for the free end will give when the normal forces of the lever are attempted to be transmitted through it.

Threaded apertures and 2| are provided, the former in the projection l4 and the latter in the main body of the blade, for the purpose of receiving a screw 22, or the like. Where the projection I4 is employed, it is returned, as is shown in Fig. 5, so as to dispose the aperture 20 beneath the aperture 2|. Apertures' 23 are provided in that end of the blade remote from the projection [4 which are adapted to receive screws 24, or the like, for the purpose of fixing the blade to a support, as 25,

The method of constructing the blade I0 is simple and provides .a blade which is effective for all of the purposes for which it is intended to be used. The strips II and I2 are preformed and are placed one against the other in superposed relation. The strips are then welded together through any of the various welding processes to provide the desired bimetallic blade. After the strips have been welded, the rib l I is pressed from. one surface thereof and apertures are stamped or otherwise made therein at predetermined points for the purpose of securing the finished blade to a support. Of course, apertures may be omitted, if desired, and the blade welded, strapped, or otherwise fixed toa support.

In Fig. 5, that portion of the blade bearing the apertures 23 is shown as returned beneath the main body which spaces the main body of the blade I6 from its support. In Fig. 6, the blade i0 is shown fixed to the support 25 and having the screw 22 in adjustable engagement with the threaded apertures 20 and 2|. Beneath the main body of the blade and extending longitudinally thereof is a lever 21 which is pivoted at an intermediate point to a support 28. A contact 29 is fixed to one end of the lever 21. A contact 30 is fixed to a plate 3| supported on the base 25, and is disposed beneath the contact 29 for cooperative make-and-break action. A spring 32 is disposed between the base 25 and that end of the lever 2'! remote from the contact 29, and serves to bias the contacts into closed relation.

The operation of the bimetallic blade as set up in Fig. 6 is obvious. Heat from any source reaching the blade It] causes the usual stresses to be set up therein. The screw 22 is moved towards the base 25 and strikes the lever 21 to rotate it in counterclockwise movement about the support 28, which breaks the engagement between the contacts 29 and 30. Upon the dissipation of heat, the bimetallic blade Ill assumes its normal position which, of course, results in the movement of the screw 22 upwardly from the base 25 to release the lever 21 and to allow the spring 32 to force the contacts 29 and 30 into operative engagement.

It is to be understood that the blade in may be of any desired configuration, that shown in Fig. 1 being only for the purpose of illustration. In many uses, the projection I4 will be unnecessary and hence would be omitted. Further, the blade may be employed as a fiat strip, such as is shown in Fig. 2, rather than of the shape disclosed in Fig. 5. The relative lengths of the metal strips II and I2 may be varied for specific blades. The blade is, of course, susceptible to a variety of installations.

It is to be understood that the foregoing description and accompanying drawing have been given by way of illustration and example and not for purposes of limitation, the invention being limited only by the following claim.

What is claimed is:

A bimetallic blade comprising two contiguous strips, one of which is of greater length than the other to provide a free extension, and means integral with the free end and the bimetallic assemblage strengthening the free end and preventing curling of the end of the bimetallic blade, said means including a longitudinally extending rib, one part of which is in the free end and the other part of which is in the bimetallic assemblage.

LAWRENCE M. PERSONS. 

